1. Field of the Invention
The present invention relates generally to a sensing assembly for an electrical switch and more particularly to an environmentally sealed sensing assembly without mechanical contacts and encapsulated in potting compound whereby it is specially suited for use in a humid, corrosive environment.
2. Description of the Prior Art
Electronic components are vulnerable to corrosion damage, which is particularly likely to occur in a warm, humid environment or in the presence of corrosive vapors. It is possible to protect electronic components such as transistors or even entire circuit boards from such an environment by encapsulating them within a waterproof and vapor-proof potting material. Potting materials suitable for this purpose and techniques for employing them are known to the art.
However, most electric switches are not amenable to protection by potting. Unlike other electronic components, most switches have mechanical contacts and depend for operation upon freedom of motion of at least one component. It is extremely difficult to design such a mechanical switch to exclude moisture or vapors without cutting off the freedom of motion necessary for the switch to function. Hence, the benefits of using potting material to protect electronic components from hostile environments have not been available for the protection of electric switches having such mechanical contacts.
Various other methods of protecting switches from the environment are known to the art. Most involve enclosure of the switch in a waterproof housing and sealing the electrical path of the mechanical connection between the switch contacts and the exterior by means of rubber boots, O-rings, gaskets or the like. Although such arrangements can seal out all moisture, they are expensive, cumbersome, and prone to failure.
Heretofore, there has been no inexpensive and simple way to construct a switch capable of enduring constant exposure to a hostile environment. For example, the switches installed adjacent to a hot tub for controlling the hot tub lights or pump are particularly vulnerable to corrosion damage because the surrounding atmosphere is warm and humid. Methods known to the art have not been adequate to protect such switches from corrosion.
U.S. Pat. No. 4,268,713, issued to Donley et al on May 19, 1981, teaches an encapsulated waterproof flasher for motor vehicle lights. The flasher has a cavity for a component such as a relay having mechanical switch contacts, but without exterior mechanical connections. Potting material completely seals the cavity to protect the relay contacts from the external environment. The Donley apparatus is representative of those systems using potting material to protect switching contacts from a moist external environment, but it is not adapted to provide for the protection of switching contacts mechanically connected to the exterior.
There is a need for a switch sensing assembly usable in proximity to a hot tub, or other moist or corrosive environment, and capable of functioning without conventional mechanical switch contacts.